EFFECT OF BONE AREA ON SPINE DENSITY IN CHINESE MEN AND WOMEN IN TAIWAN

Areal hone mineral density (BMD), the quotient of bone mineral content (BMC) divided by the projectional bone area (BA), measured with dual- energy X-ray absorptiometers (DXA), is the most common parameter used today to evaluate spinal osteoporosis, To evaluate whether gender, age , weight, and height can determine spinal BA, and to compare BA and an alyze its effects on spinal density in the two genders, we measured BA and BMC, and calculated areal BMD, and the bone mineral apparent dens ity (BMAD = BMD/root BA) of the L-2 to L-4 vertebrae of 604 female and 223 male Chinese volunteers from 20 to 70 years of age using a Norlan d XR-26 DXA. Standardized for height and weight, BA showed a relativel y large variation and a significant increase with increasing age in bo th genders, On the other hand, BMC stayed unchanged in men >50 years o f age and decreased with aging in post-menopausal women. Younger men ( <51 years) had a much Larger mean BA (by 15.5%) and larger mean BMC (o nly 10%) than that of age-matched women, As a result, younger men had a slightly and significantly lower areal BMD (by 7.1% and a much lower BMAD (by 16%) (p < 0.0001 for both than premenopausal women of simila r age, Men had higher areal BMD and BMAD values than age-matched women only after age 50 years, Although taller body height, heavier weight, and increasing age were associated with a larger BA, these factors co uld not explain most of the interindividual variations in BA in both g enders, Thus anteroposterior BA of lumbar vertebrae measured with DXA seems to affect the areal BMD and BMAD readings in the two genders, Th e larger Brl caused a low BMAD and probably underestimated the true vo lumetric spine density in men. (C) 1997 by Elsevier Science Inc. All r ights reserved.